Fixed: Application crashes when opening the random article.

[MohitMaliFtechiz]

Fixes #4161

• The issue occurred in the Play Store variant, specifically with the copy/move functionality for ZIM files. After copying or moving a ZIM file, the application attempts to open it in the reader. However, if the application tries to open a split ZIM file with only one chunk, it throws an error indicating that the file is not a valid ZIM file (which is expected, as not all ZIM chunks have been copied/moved). When this error occurs, the menu buttons remain enabled, allowing the user to interact with them. If the user then attempts to open a random article, the application enters an infinite loop and crashes. To resolve this, we now disable the menu controls whenever an error occurs while opening a ZIM file, preventing the user from using them in such scenarios.

Before fix

screen-20250108-154820.mp4

After fix

screen-20250108-152814.mp4

• Added a retry mechanism to attempt fetching the random article twice in case of an internal error in libzim to prevent going into an infinite loop.
• After two failed attempts, an error message is displayed to the user if the random article is not found.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 56.79%. Comparing base (283d845) to head (cdafdba).

Files with missing lines	Patch %	Lines
.../kiwix/kiwixmobile/core/main/CoreReaderFragment.kt	0.00%	12 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4162      +/-   ##
============================================
- Coverage     56.93%   56.79%   -0.15%     
+ Complexity     1518     1516       -2     
============================================
  Files           313      313              
  Lines         13402    13413      +11     
  Branches       1666     1668       +2     
============================================
- Hits           7631     7618      -13     
- Misses         4614     4650      +36     
+ Partials       1157     1145      -12     

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[kelson42]

@MohitMaliFtechiz Why the reader handle should be or is null? If there is a valid scenario, then we should have a generoc function trsting this and this should be builtin in the ZIM reader class at all places where needed. I don't understand why such a basic thing is done at such a high level!?

[MohitMaliFtechiz]

@MohitMaliFtechiz Why the reader handle should be or is null?

@kelson42 No it will not be null if there is a ZIM file opened in the reader. The controls are disabled until the ZIM file is not loaded into the webView. Actually, the error occurs when we are copying/moving the split ZIM file so after copying/moving the ZIM file it tries to open the ZIM file in the reader but currently, it is corrupted since all ZIM chunks are not copied and the reader showing invalid ZIm file. But at this moment, menu controls are enabled for this ZIM and the user tries to open the random article, so in this condition, the reader was null, and openRandomArticle was going into an infinite loop. I have placed a fix for it and updated the videos on the PR description.

[MohitMaliFtechiz]

The Ci is failing due to #4169.